A wide variety of seats is provided with components which allow at least a portion of the seat to be adjusted. Examples for such adjustable portions include adjustable lumbar supports, adjustable side supports or various massage functions. Seats which provide a user with the option to adjust at least a portion of the seat are used to provide enhanced comfort. This may be of particular importance when a user may be likely to sit on the seat for an extended time period. A typical example is a seat for use in transportation, e.g. a car seat or another vehicle seat. For illustration, for car seats, bus seats or other public transportation seats, the seat occupant may spend an extended time period sitting on the respective seat.
In order to accommodate different passenger sizes, it is desirable to provide a seat which allows a seat cushion size to be adjusted. This can be attained by increasing and/or decreasing a length of a seat cushion. The seat cushion upon which the user's thighs rest may thereby be adjusted in its length, measured along the forward-rearward direction of the seat, for example.
Motor-driven adjusting devices offer various advantages over manual adjustment devices. User comfort may be enhanced. Motor-driven adjusting devices also provide an electric interface which lends itself to automation, e.g. under the control of a controller of a vehicle which may automatically control the motor to bring the seat to a desired state. In spite of the benefits offered by motor-driven adjusting devices, packaging is an issue in many seats. In vehicle seats, it may be desired that a large number of components can be integrated into the seat to provide various comfort functions, such as adjustable side support in combination with seat cushion length adjustment. The size and weight of a motor used in conventional seat adjusting devices may add to the size and weight of the seat. Conventional motor-driven adjusting devices may also be complex to install and may not be configured to allow the characteristics of the adjusting device to be easily adapted to different customer needs. The resulting workload increases the costs of the seat. The construction of conventional adjusting devices, which may be based on fairly rigid and sturdy linear actuators, may be prone to breakage under the loads encountered in seating, e.g. in a vehicle seat.